I experienced Outlook 2011 freeze immediately following upgrade to OS X El Capitan.
I resolved this issue by rebuilding my Identity Database.
1. Launch the Microsoft Database Utility from the Microsoft Office 2011 Program Group.
2. Select "Main Identity" from the list of available identity databases
3. Click "Rebuild"
I was able to immediately open Outlook 2011 and synchronize with Exchange Server.
If this fails, you may attempt to rebuild a backup database and set it to Default.
I look forward to hearing if this works for others, as this appears to be affecting may people.